Epoxidized ester additives for reducing lead corrosion in lubricants and fuels

ABSTRACT

Fuels, especially hydrocarbon fuels, and lubricants, especially lubricating oils, contain a class of anti-corrosion, anti-fatigue, and anti-wear additives that are derived epoxidized esters of fatty acids. Epoxidized 2-ethylhexyl tallate is particularly effective.

I claim the benefit under Title 35, United States Code, § 120 of U.S. Provisional Application No. 60/623,036, filed Oct. 29, 2004, entitled EPOXIDIZED ESTER ADDITIVES FOR REDUCING LEAD CORROSION IN LUBRICANTS AND FUELS.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is related to fuels, especially hydrocarbon fuels, and lubricants, especially lubricating oils, and, more particularly, to a class of anti-corrosion additives that are derived from epoxidized esters for such fuels and lubricants.

2. Description of Related Art

In developing lubricating oils, there have been many attempts to provide additives that protect metal engine parts from corrosion. Metal corrosion may variously result from the corrosivity of the lubricant itself or, more frequently, from corrosive additives that are added to the lubricant formulation to impart other desired properties, such as anti-wear and extreme pressure protection. Corrosion may also be due to contaminants, such as water and combustion by-products, that are normally present in the engine.

Engine bearings are particularly prone to corrosion, especially copper-lead bearings. It is important to protect these bearings from corrosion, as bearing corrosion can lead to wear, increased friction, lost fuel economy, and, ultimately, catastrophic engine failure. Lead that is leached from the bearings by corrosion contaminates the oil and poses additional environmental problems from particulate emissions and toxic waste pollution. It is important to limit the particulate matter and pollution formed during engine use for toxicological and environmental reasons, but it is also important to maintain undiminished the anti-wear properties of the lubricating oil.

A number of additives are known, such as 2-mercaptobenzothiazole and benzotriazoles, that can be added to an oil formulation in order to provide anti-corrosion protection to copper. Very little can be done, however, to protect against materials that are corrosive to lead. Only a limited number of additives are known that reduce lead corrosion.

Known lead anti-corrosion additives include 2,5-dimercapto-1,3,4-thiadiazole and derivatives thereof, terephthalic acid, and dithiophosphoric acid derivatives. The known lead anti-corrosion additives are not satisfactory. Many of these additives are expensive, being prepared by multi-step processes from costly starting materials. Some have limited solubility in oils, and may react with basic detergent/dispersant components. Others contain phosphorus, which is undesirable in its own right, as phosphorus is suspected of limiting the service life of the catalytic converters that are used on cars to reduce pollution.

Zinc dialkyldithiophosphates (ZDDP) have been used in formulated oils as anti-wear additives for more than 50 years. However, zinc dialkyldithiophosphates give rise to ash, which contributes to particulate matter in automotive exhaust emissions, and regulatory agencies are seeking to reduce emissions of zinc into the environment. Therefore, it is desirable to promote the use of alternative phosphorus-free anti-wear additives.

U.S. Pat. No. 2,783,202 discloses reacting a low molecular weight epoxide with a solution of bis(sulfurized oleyl) dithiophosphoric acid to produce an additive that inhibits corrosion of copper-lead and cadmium-silver bearings.

U.S. Pat. No. 2,783,203 discloses that the reaction products of dialkyl dithiophosphoric acid with styrene oxide inhibited the corrosiveness of the lubricant toward the surfaces of copper-lead bearings.

U.S. Pat. No. 2,991,251 discloses the use of 2-mercaptobenzothiazole or salicylic acid, combinations thereof, or salicylic acid/butylamine as anti-corrosive agents for lead in copper lead bearings lubricated with fatty acid partial esters of aliphatic polyhydric alcohols, e.g., sorbitan mono-oleate.

U.S. Pat. No. 3,223,636 discloses inhibitors which are obtained by incomplete reaction of 1-4 moles of an alcohol. such as methanol, ethanol, propanol, or iso-propanol with one mole of an aliphatic dicarboxylic acid of 6-12 C atoms such as adipic, azelaic, or sebacic. The inhibitor reduces lead loss from lead bearings in aircraft engines lubricated with synthetic ester lubricants.

U.S. Pat. No. 3,413,227 discloses 5-substituted benzotriazoles as corrosion inhibitors for lubricants.

U.S. Pat. No. 3,597,353 discloses 4,5,6,7 tetrahydro-benzotriazoles as corrosion inhibitors for lubricants.

U.S. Pat. No. 3,625,894 discloses an anticorrosive for lubricants consisting of an alkaline earth metal sulfonate, and/or an oil-soluble alkaline earth metal salt of a fatty acid having from 10 to 36 carbon atoms, and/or an oil-soluble alkaline earth metal salt of an alkyl-sulfamido-carboxylic acid, and benzotriazole.

U.S. Pat. No. 3,966,623 discloses a lubricating oil composition containing a synergistic corrosion inhibiting combination of 2,5-bis-hydrocarbyldithio-1,3,4-thiadiazole and a primary alkyl or alkenyl amine salt of 2-mercaptobenzothiazole.

U.S. Pat. No. 4,153,565 discloses lubricant compositions containing oleaginous materials and, in amounts sufficient to impart oxidation protection, corrosion resistance and antiwear properties thereto, an adduct of a benzotriazole compound and alkyl vinyl ether or a vinyl ester of a carboxylic acid.

U.S. Pat. No. 4,193,882 discloses lubricant compositions containing, in an amount sufficient to inhibit metal corrosion, the reaction product of oleic acid and 2,5-dimercapto-1,3,4-thiadiazole.

U.S. Pat. No. 4,382,869 discloses that dimercaptothiadiazole adducts of hydroxyl-containing unsaturated compounds and their borated analogues provide effective multifunctional friction reducing and corrosion inhibiting properties to various lubricating fluids when incorporated therein.

U.S. Pat. No. 4,349,445 discloses the use of certain dithiophosphates as lubricant antioxidants and anti-corrosion agents.

U.S. Pat. No. 4,410,436 discloses lubricating compositions containing copper and lead corrosion inhibitors and boron and/or metal-boron derivatives having extreme pressure, anti-wear and friction reducing properties.

U.S. Pat. No. 4,427,560 discloses lubricating compositions containing an oxidation inhibitor, copper and lead corrosion inhibitors and boron and/or metal-boron derivatives having extreme pressure, anti-wear and friction reducing properties.

U.S. Pat. No. 4,501,677 discloses a lubricating oil composition with improved corrosion inhibiting properties comprising a major amount of a lubricating oil basestock and an effective amount of a complex of a selected heterocyclic nitrogen compound and an organometallic salt of a C₄ to C₂₂ fatty acid.

U.S. Pat. No. 4,522,785 discloses a process for minimizing corrosion of metals in contact with aqueous acid solutions wherein said process comprises adding to the aqueous acid solution a corrosion inhibiting amount of a dialkylaminomethyl aromatic triazole having the structure:

wherein R₁ is from 1 to 4 substituents and is hydrogen, aliphatic of 1 to about 12 carbons, alkoxy of 2 to about 10 carbons, aroxy of 2 to about 10 carbons, or —COOR₄ wherein R₄ is aliphatic of 1 to about 12 carbons; and R₂ and R₃ are the same or different and are alkyl of 1 to about 4 carbons.

U.S. Pat. No. 4,618,539 discloses corrosion-inhibiting compositions which comprise a mixture of (A) at least one oil-soluble neutral or basic alkali metal or alkaline earth metal salt or complex of at least one organic acid, and (B) a nitrogen- and boron-containing composition which is the reaction product of at least one amino alcohol, at least one of a boric acid or boron trioxide, and at least one organic carboxylic acid. Such compositions are said to exhibit improved corrosion-inhibiting properties, especially when included in preservative oil applications. The composition may also contain a mixture of calcium and barium salts of one or more organic sulfonic acids.

U.S. Pat. No. 4,705,642 discloses a haze, oxidation, and corrosion resistant diesel engine lubricant composition, said to be particularly useful in marine and railway diesel engines, that contains 0.1-5.0 weight percent of a reaction product additive. The reaction product additive is produced by first reacting substantially equimolar amounts of an anhydride compound which is either a dibasic acid anhydride or isatoic anhydride and a hydrocarbon-substituted mono primary amine or ether amine at a temperature range of 50° C.-150° C. to produce an intermediate reaction product. The intermediate reaction product is thereafter further reacted at an elevated temperature with a substantially equimolar amount of a heterocyclic azole or polyalkylene polyamine compound to form the final reaction product.

U.S. Pat. No. 4,735,735 discloses a method for corrosion inhibition in oil or oil emulsions comprising adding thereto a corrosion-inhibition-effective amount of at least one salt corresponding to the general formula

in which R₁ is a linear or branched C₈₋₃₆ alkyl or C₈₋₃₆ alkenyl or a mono- or polyethoxylated C₈₋₁₈ alkyl containing from 1 to 10 ethoxy groups, R₂ is a linear or branched C₁₀₋₂₀ alkyl and M is half an equivalent of a divalent metal which is magnesium, calcium, barium, or zinc.

U.S. Pat. No. 4,752,406 discloses 3-(4-alkylbenzoyl)-acrylic acids corresponding to the formula

in which R is straight-chain or branched-chain C₈-C₁₈ alkyl, or mixtures thereof, which are said to be useful as corrosion inhibitors in lubricating oils and lubricating greases based on mineral oils.

U.S. Pat. No. 4,758,363 discloses an oxidation and corrosion resistant diesel engine lubricant composition comprising a major amount of a base hydrocarbon lubricating oil and from 0.1-5.0 weight percent of a reaction product additive which is the reaction product obtained by first reacting a hydroxybenzoic acid and a polyoxyalkylene polyol to form an ester, and thereafter reacting the ester with an aldehyde or ketone and a substituted or unsubstituted heterocyclic azole to produce the final reaction product.

U.S. Pat. No. 4,808,335 discloses an oxidation and corrosion resistant diesel engine lubricant composition comprising a major amount of a base hydrocarbon lubricating oil and from 0.1-5.0 weight percent of a reaction product additive which is the reaction product of an N-acyl sarcosine and a substituted or unsubstituted heterocyclic azole.

U.S. Pat. No. 4,981,604 discloses an oxidation and corrosion resistant diesel engine lubricant composition comprising a major amount of a base hydrocarbon lubricating oil and from 0.1-5.0 weight percent of a reaction product additive which is the reaction product of a dibasic acid anhydride, a polyoxyalkylene diamine, and a heterocyclic azole.

U.S. Pat. No. 5,171,462 discloses that mixtures of block alkoxy co- or terpolymer hydrocarboxylates and aminopolyazole increase the oxidation and corrosion resistance of lubricants.

U.S. Pat. No. 5,308,521 discloses an additive composition of (a) a substituted aromatic triazole and (b) a hydrocarbyl substituted succinic acylated polyamine dispersant, reacted with a boron compound that is said to impart improved corrosion resistance to lubricating oils which contain a multifunctional olefin copolymer viscosity index modifier.

U.S. Pat. No. 5,368,776 discloses a method for improving the corrosion inhibition of lubricating oils especially those of vegetable origin which comprises adding an efficient amount of the reaction product of an epoxidized fatty acid ester, especially an epoxidized methyl ester of an unsaturated fatty acid and a sulphonic acid.

U.S. Pat. No. 5,681,506 discloses a corrosion inhibiting lubricating composition comprises: (a) a synthetic ester base stock; (b) at least one aromatic amine antioxidant; (c) a neutral organic phosphate of the formula (R¹O)₃PO where R¹ is a tolyl, phenyl, xylyl, alkyl or cycloalkyl group, the alkyl or cycloalkyl group having up to 10 carbon atoms; (d) a saturated or unsaturated dicarboxylic acid of a given general formula (e) a straight or branched chain saturated or unsaturated monocarboxylic acid which is optionally sulphurised or an ester of such an acid; and (f) a triazole.

U.S. Pat. No. 6,281,174 discloses lubricating compositions which contain organomolybdenum compounds and sulfur compounds (donors). The copper corrosion of said compositions is reduced by reacting the sulfur donors with plant oils to reduce sulfur activity and thus copper corrosion prior to the sulfur donors being added to the majority of oil to form a lubricating composition.

WIPO Publication No. 2002086011 discloses the use of 3,4-epoxycyclohexanecarboxylates, especially the trioxyethylene, tetraoxyethylene, and pentaoxyethylene esters of 3,4-epoxycyclohexanecarboxylic acid as seal swell stabilizers and acid scavengers for organic phosphate ester aircraft hydraulic fluids.

Polina, E. V.; et al, (Sb. Tr. VNII po Pererab. Nefti, 29:13-17 (1978); CAN 92:200582 discloses that the addition of epoxy compounds to pentaerythritol esters used as turbine lubricants decreases their corrosive action on brass.

DE 1954452 discloses the use of epoxidized fatty esters (e.g. epoxidized butyl or octyl oleate) as lubricant additives to decrease wear and friction.

SUMMARY OF THE INVENTION

It has now been found that epoxidized esters, epoxidized diesters, and epoxidized triesters (hereinafter collectively termed “epoxidized esters”) are useful as lubricant additives, imparting anti-corrosive properties to the lubricant that protect lead and copper from corrosion. The epoxidized ester additives impart protection to the lubricated system against the corrosive tendencies of other additives that might otherwise be desirable to add to the lubricant, such as glycerol mono-oleate, which is useful as a phosphorus-free friction modifier and anti-wear agent.

The present invention also relates to lubricating oil compositions comprising a lubricating oil, a functional property-improving amount of at least one epoxidized ester, and, optionally, an additive that is corrosive to lead and/or copper.

It is an object of the present invention to provide a new application for epoxidized esters useful either alone or in combination with other lubricant additives. The epoxidized esters in combination with any of: glycerol monooleate, partially hydrolyzed vegetable oils, full and partial esterification products of diols and polyols with and C₆-C₃₆ carboxylic acids, C₆-C₅₀ carboxylic acids, amides derived from C₆-C₅₀ carboxylic acids, esters of hydroxypolycarboxylic acids, tetraalkyl thiuram disulfides, thionamides, thioureas, dithiocarbamates, hydrazides, succinylhydrazides, 4-imidazolidine thiones, 1,3,4-oxadiazole-2(3H)-thiones, 1,3,4-thiadiazolane-2-thiones, 2,3-dihydro-1,3,4-oxadiazoles, and the mixed thio acid amide molybdenum complexes available as an article of commerce from Crompton Corporation as Naugalube® MOlyFM™ 2543 are an improvement over the prior art.

The epoxidized esters of the present invention have the following generic formula:

wherein:

m is 1 to 36, preferably 1 to 12;

R₁ and R₂ are independently selected hydrocarbyl groups, preferably of from 1 to 50 carbon atoms, more preferably of from 1 to 18 carbon atoms, which may be further substituted with alkyl, cycloalkyl, alkenyl, aryl, or alkoxy groups, and may contain OH, ether or epoxide functionalities,

or R₁ is a polyol residue selected from the group consisting of

wherein:

n is O to about 12;

R₄, R₅, and R₉ are independently selected from the group consisting of hydrogen and hydrocarbyl, preferably alkyl;

R₆ is selected from the group consisting of linear alkylene, branched alkylene, linear alkenyl, and branched alkenyl;

R₃, R₇, and R₈ are independently selected from the group consisting of hydrogen and an acyl group of the form:

wherein R₁₀ is hydrocarbyl of 1 to 36, preferably 1 to about 18 carbon atoms, which may be further substituted, preferably with alkyl, cycloalkyl, alkenyl, aryl, or alkoxy groups, and may contain OH, ether, or epoxide functionalities.

As employed herein, the term “hydrocarbyl” includes hydrocarbon as well as substantially hydrocarbon groups. “Substantially hydrocarbon” describes groups that contain heteroatom substituents that do not alter the predominantly hydrocarbon nature of the group.

Examples of hydrocarbyl groups include the following:

(1) hydrocarbon substituents, i.e., aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, aromatic substituents, aromatic-, aliphatic-, and alicyclic-substituted aromatic substituents, and the like, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (that is, for example, any two indicated substituents may together form an alicyclic radical);

(2) substituted hydrocarbon substituents, i.e., those substituents containing non-hydrocarbon groups which, in the context of the present invention, do not alter the predominantly hydrocarbon nature of the substituent; those skilled in the art will be aware of such groups (e.g., halo, hydroxy, mercapto, nitro, nitroso, sulfoxy, etc.);

(3) heteroatom substituents, i.e., substituents that will, while having a predominantly hydrocarbon character within the context of the present invention, contain an atom other than carbon present in a ring or chain otherwise composed of carbon atoms (e.g., alkoxy or alkylthio). Suitable heteroatoms will be apparent to those of ordinary skill in the art and include, for example, sulfur, oxygen, nitrogen, and such substituents as, e.g., pyridyl, furyl, thienyl, imidazolyl, etc. Preferably, no more than about 2, more preferably no more than one, hetero substituent will be present for every ten carbon atoms in the hydrocarbyl group. Most preferably, there will be no such heteroatom substituents in the hydrocarbyl group, i.e., the hydrocarbyl group is purely hydrocarbon.

More particularly, the present invention is directed to a composition comprising:

(A) a lubricant or a hydrocarbon fuel, and

(B) at least one epoxidized ester of formula:

-   -   wherein:     -   m is 1 to 36, preferably 1 to 12;     -   R₁ and R₂ are independently selected hydrocarbyl groups,         preferably of from 1 to 50 carbon atoms, more preferably of from         1 to 18 carbon atoms, which may be further substituted with         alkyl, cycloalkyl, alkenyl, aryl or alkoxy groups, and may         contain OH, ether or epoxide functionalities,

or R₁ is a polyol residue selected from the group consisting of

-   -   wherein:

n is 0 to about 12;

R₄, R₅, and R₉ are independently selected from the group consisting of hydrogen and hydrocarbyl;

R₆ is selected from the group consisting of linear alkylene, branched alkylene, linear alkenyl, and branched alkenyl;

R₃, R₇, and R₈ are independently selected from the group consisting of hydrogen and an acyl group of the form:

wherein R₁₀ is hydrocarbyl, which may be further substituted.

In another embodiment, the present invention is directed to a method for improving the anti-corrosive. anti-fatigue, and anti-wear properties of lubricants and hydrocarbon fuels comprising adding to said lubricants and hydrocarbon fuels a functional property-improving amount of at least one at least one epoxidized ester of the formula:

wherein R₁, R₂, and m are as described above.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As stated above, the class of anti-fatigue, anti-wear, and extreme pressure additives can have the following formula:

wherein R₁, R₂, and m are as described above.

Preferably, in the formulae described above, R₁ is hydrocarbyl and R₄, R₅, and R₉ are either hydrocarbyl or hydrogen. Examples of R₁, R₄, R₅, and R₉ include, but are not limited to, straight chain or branched chain alkyl or alkenyl groups containing from one to fifty carbon atoms, including, but not limited to, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethyl hexyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, oleyl, nonadecyl, eicosyl, heneicosyl, docosyl, tricosyl, tetracosyl, pentacosyl, triacontyl, isomers of the foregoing, and the like;

cyclic alkyl groups, such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and cyclododecyl;

unsubstituted phenyl;

phenyl substituted with one or more alkyl groups, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, isomers of the foregoing, and the like;

phenyl substituted with one or more alkoxy groups, such as methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonoxy, decoxy, isomers of the foregoing, and the like;

phenyl substituted with one or more alkyl amino or aryl amino groups; and

naphthyl and alkyl substituted naphthyl.

R₆ is a disubstituted moiety derived from, among other species, straight chain or branched chain alkylene or alkenyl groups containing from one to fifty carbon atoms, including, but not limited to, methylene, ethylene, propylene, butylene, pentylene, hexylene, heptylene, octylene, 2-ethylhexylene, nonylene, decylene, undecylene, dodecylene, tridecylene, tetradecylene, pentadecylene, hexadecylene, heptadecylene, octadecylene, oleylene, nonadecylene, eicosylene, heneicosylene, docosylene, tricosylene, tetracosylene, pentacosylene, triacontylene, isomers of the foregoing, and the like;

cyclic alkyl groups, such as cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, and cyclododecyl;

unsubstituted phenyl;

phenyl substituted with one or more alkyl groups, such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, isomers of the foregoing, and the like;

phenyl substituted with one or more alkoxy groups, such as methoxy, ethoxy, propoxy, butoxy, pentoxy, hexoxy, heptoxy, octoxy, nonoxy, decoxy, isomers of the foregoing, and the like;

phenyl substituted with one or more alkyl amino or aryl amino groups;

naphthyl and alkyl substituted naphthyl.

is a residue derived from carboxylic acid, including but not limited to: acetic, propanoic, butanoic, pentanoic, hexanoic, heptanoic, octanoic, nonanoic, decanoic, undecanoic, dodecanoic, tridecanoic, tetradecanoic, pentadecanoic, hexadecanoic, heptadecanoic, octadecanoic, nonadecanoic, eicosanoic, heneicosanoic, docosanoic, tricosanoic, tetracosanoic, pentacosanoic, triacontanoic, isomers of the foregoing, and the like, and unsaturated and polyunsaturated analogs of the foregoing, such as oleic, linoleic, ricinoleic, eleostearic, and linolenic, acrylic, crotonic, pentenoic, hexenoic, heptenoic, octenoic, nonenoic, decenoic, undecenoic, dodecenoic, tridecenoic, tetradecenoic, pentadecenoic, hexadecenoic, heptadecenoic, octadecenoic, nonadecenoic, eicosenoic, heneicosenoic, docosenoic, tricosenoic, tetracosenoic, pentacosenoic, and triacontenoic.

is a residue derived from an unsaturated or polyunsaturated carboxylic acid, such as oleic, linoleic, ricinoleic, eleostearic, and linolenic, acrylic, crotonic, pentenoic, hexenoic, heptenoic, octenoic, nonenoic, decenoic, undecenoic, dodecenoic, tridecenoic, tetradecenoic, pentadecenoic, hexadecenoic, heptadecenoic, octadecenoic, nonadecenoic, eicosenoic, heneicosenoic, docosenoic, tricosenoic, tetracosenoic, pentacosenoic, triacontenoic,

More preferably,

is a residue derived from an unsaturated or polyunsaturated carboxylic acid, such as oleic, linoleic, ricinoleic, eleostearic, and linolenic, dodecenoic, tridecenoic, tetradecenoic, pentadecenoic, hexadecenoic, heptadecenoic, octadecenoic, nonadecenoic, eicosenoic, heneicosenoic, and docosenoic.

R₁ is selected from the group consisting of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, 2-ethyl hexyl, nonyl, decyl, undecyl, dodecyl, isomers of the foregoing, and the like, or

R₁ is a polyol residue, or a polyol residue that is partially or fully esterified with a residue that is derived from a carboxylic acid such as: dodecanoic, tridecanoic, tetradecanoic, pentadecanoic, hexadecanoic, heptadecanoic, octadecanoic, nonadecanoic, eicosanoic, heneicosanoic, docosanoic, isomers of the foregoing, and the like, and unsaturated and polyunsaturated analogs of the foregoing, such as oleic, linoleic, ricinoleic, eleostearic, and linolenic, dodecenoic, tridecenoic, tetradecenoic, pentadecenoic, hexadecenoic, heptadecenoic, octadecenoic, nonadecenoic, eicosenoic, heneicosenoic, docosenoic; wherein said carboxylic acid residue may optionally be substituted with OH or epoxide (oxirane).

R₁ and

can be residues that are derived from epoxidized vegetable oils, such as canola (rapeseed), corn, cottonseed, castor, coconut, linseed, palm, palm kernel, peanut, safflower, soybean, sunflower, and tung oils, epoxidized animal oils, such as tallow, and epoxidized tall oil; any or all of which may be partially or fully hydroxlyzed or transesterified, or mixtures thereof.

Most preferably, R₁ is alkyl or branched alkyl of 4 to 12 carbons and

is a residue derived from oleic or linoleic acid, or mixtures thereof, such as epoxidized 2-ethyl hexyl tallate, epoxidized octyl oleate or epoxidized butyl oleate; or R₁ and

are residues derived from the following epoxidized oils: soybean, canola (rapeseed), corn, cottonseed, linseed, palm, palm kernel, peanut, safflower, soybean, sunflower and tallow.

The use of the epoxidized esters of the present invention can improve the anti-corrosion, anti-fatigue, and anti-wear properties of a lubricant, especially the anti-corrosive properties of a lubricant with respect to lead.

Suitable epoxidized esters for use in the practice of the present invention include epoxidized methyl tallate, epoxidized butyl tallate, epoxidized 2-ethylhexyl tallate, epoxidized octyl tallate, and epoxidized methyl oleate, epoxidized butyl oleate, epoxidized 2-ethylhexyl oleate, epoxidized octyl oleate, and the like; epoxidized methyl linoleate, epoxidized butyl linoleate, epoxidized 2-ethylhexyl linoleate, epoxidized octyl linoleate and the like; epoxidized unsaturated oils, such as epoxidized soybean oil, epoxidized canola oil, and the like; epoxidized corn oil, epoxidized cottonseed oil, epoxidized linseed oil, epoxidized palm oil, epoxidized palm kernel oil, epoxidized peanut oil, epoxidized safflower oil, epoxidized soybean oil, epoxidized sunflower oil, and epoxidized tallow.

Other suitable esters include the mono- and diesters of diols such as ethylene glycol, 1,2-propane diol, 1,3-propediol, 1,2-butanediol, 1,3-butanediol, 1,4-butane diol, 1,6-hexane diol, (and the like), with decanoic acid, epoxidized dodecanoic acid, epoxidized tetradecanoic acid, epoxidized hexadecanoic acid, epoxidized octadecanoic acid, epoxidized oleic acid, epoxidized linoleic acid, epoxidized tall oil, and the like.

Other suitable esters include the mono-, di- and triesters of triols, such as glycerol, trimethylolpropane (and the like), with decanoic acid, epoxidized dodecanoic acid, epoxidized tetradecanoic acid, epoxidized hexadecanoic acid, epoxidized octadecanoic acid, epoxidized oleic acid, epoxidized linoleic acid, epoxidized tall oil, and the like.

Other suitable esters include the mono-, di-, tri- and tetraesters of pentaerythritol with decanoic acid, epoxidized dodecanoic acid, epoxidized tetradecanoic acid, epoxidized hexadecanoic acid, epoxidized octadecanoic acid, epoxidized oleic acid, epoxidized linoleic acid, epoxidized tall oil, and the like.

Especially preferred epoxidized additives for use in the practice of the present invention include: epoxidized butyl tallate, epoxidized 2-ethyl hexyl tallate, epoxidized octyl tallate, epoxidized butyl oleate, epoxidized 2-ethyl hexyl oleate, epoxidized octyl oleate, epoxidized soybean oil, and epoxidized canola oil.

The epoxidized ester additives are readily prepared from unsaturated esters and polyesters. The polyesters include unsaturated and polyunsaturated vegetable oils, such as canola (rapeseed), corn, cottonseed, castor, coconut, linseed, palm, palm kernel, peanut, safflower, soybean, sunflower, and tung oils; and esters derived from the hydrolysis of unsaturated fats and oils, e.g., oleates, linoleates, ricinoleates, eleostearates, and linolenates. Epoxidized soybean oil is an article of commerce available from Crompton Corporation as Drapex® 6.8. Epoxidized linseed oil is an article of commerce available from Crompton Corporation as Drapex 10.4.

A particularly preferred class of esters, known as tallates, can be derived from “Tall Oil Fatty Acid”, a by-product of the Kraft paper manufacturing process. (See “Chemical Process Technology Encyclopedia”, Douglas M. Considine, Ed., McGraw Hill, New York, 1974 pp 1129-1135). Epoxidized 2-ethylhexyl tallate is an article of commerce available from Crompton Corporation as Drapex 4.4.

The additives of the current invention can be used in combination with other additives typically found in motor oils. The typical additives found in motor oils include dispersants, detergents, anti-wear agents, extreme pressure agents, rust inhibitors, antioxidants, antifoamants, friction modifiers, Viscosity Index improvers, metal passivators, and pour point depressants.

The epoxidized ester additives of the present invention can be used as either partial or complete replacements for the anti-corrosion agents currently used. Examples of anti-corrosion/rust agents include 2-mercaptobenzothiazole, benzotriazoles, 2,5-dimercapto-1,3,4-thiadiazole and derivatives thereof, terephthalic acid, and dithiophosphoric acid derivatives.

The epoxidized ester additives of the present invention can be used in combination with other additives typically found in lubricating oils, as well as with other anti-corrosion additives. The additives typically found in lubricating oils are, for example, dispersants, detergents, corrosion/rust inhibitors, antioxidants, anti-wear agents, anti-foamants, friction modifiers, seal swell agents, demulsifiers, viscosity index (VI) improvers, pour point depressants, and the like. See, for example, U.S. Pat. No. 5,498,809 for a description of useful lubricating oil composition additives, the disclosure of which is incorporated herein by reference in its entirety.

Examples of dispersants include polyisobutylene succinimides, polyisobutylene succinate esters, Mannich Base ashless dispersants, and the like. Examples of detergents include metallic and ashless alkyl phenates, metallic and ashless sulfurized alkyl phenates, metallic and ashless alkyl sulfonates, metallic and ashless alkyl salicylates, metallic and ashless saligenin derivatives, and the like.

Examples of antioxidants include alkylated diphenylamines, N-alkylated phenylenediamines, phenyl-α-naphthylamine, alkylated phenyl-α-naphthylamine, dimethyl quinolines, trimethyldihydroquinolines and oligomeric compositions derived therefrom, hindered phenolics, alkylated hydroquinones, hydroxylated thiodiphenyl ethers, alkylidenebisphenols, thiopropionates, metallic dithiocarbamates, 1,3,4-dimercaptothiadiazole and derivatives, oil soluble copper compounds, and the like. The following are exemplary of such additives and are commercially available from Crompton Corporation: Naugalube® 438, Naugalube 438L, Naugalube 640, Naugalube 635, Naugalube 680, Naugalube AMS, Naugalube APAN, Naugard PANA, Naugalube TMQ, Naugalube 531, Naugalube 431, Naugard® BHT, Naugalube 403, and Naugalube 420, among others.

Examples of anti-wear agents include organo-borates, organo-phosphites, organo-phosphates, organic sulfur-containing compounds, sulfurized olefins, sulfurized fatty acid derivatives (esters), chlorinated paraffins, zinc dialkyldithiophosphates, zinc diaryldithiophosphates, dialkyldithiophosphate esters, diaryl dithiophosphate esters, phosphosulfurized hydrocarbons, and the like. The following are exemplary of such additives and are commercially available from The Lubrizol Corporation: Lubrizol 677A, Lubrizol 1095, Lubrizol 1097, Lubrizol 1360, Lubrizol 1395, Lubrizol 5139, and Lubrizol 5604, among others; and from Ciba Corporation: Irgalube 353.

Examples of friction modifiers include fatty acid esters and amides, organo molybdenum compounds, molybdenum dialkyldithiocarbamates, molybdenum dialkyl dithiophosphates, molybdenum disulfide, tri-molybdenum cluster dialkyldithiocarbamates, non-sulfur molybdenum compounds and the like. The following are exemplary of molybdenum additives and are commercially available from R. T. Vanderbilt Company, Inc.: Molyvan A, Molyvan L, Molyvan 807, Molyvan 856B, Molyvan 822, Molyvan 855, among others. The following are also exemplary of such additives and are commercially available from Asahi Denka Kogyo K.K.: SAKURA-LUBE 100, SAKURA-LUBE 165, SAKURA-LUBE 300, SAKURA-LUBE 310G, SAKURA-LUBE 321, SAKURA-LUBE 474, SAKURA-LUBE 600, SAKURA-LUBE 700, among others. The following are also exemplary of such additives and are commercially available from Akzo Nobel Chemicals GmbH: Ketjen-Ox 77M, Ketjen-Ox 77TS, among others. Naugalube MolyFM 2543 is also exemplary of such additives and is commercially available from Crompton Corporation. Trinuclear molybdenum dithiocarbamates, as described in U.S. Pat. No. 6,110,878, are also exemplary molybdenum additives.

An example of an anti-foamant is polysiloxane, and the like. Examples of rust inhibitors are polyoxyalkylene polyol, benzotriazole derivatives, and the like. Examples of VI improvers include olefin copolymers and dispersant olefin copolymers, and the like. An example of a pour point depressant is polymethacrylate, and the like.

Lubricant Compositions

The additives of the present invention are especially useful as components in many different lubricating oil compositions. The additives can be included in a variety of oils with lubricating viscosity including natural and synthetic lubricating oils and mixtures thereof. The additives can be included in crankcase lubricating oils for spark-ignited and compression-ignited internal combustion engines. The compositions can also be used in gas engine lubricants, turbine lubricants, automatic transmission fluids, gear lubricants, compressor lubricants, metal-working lubricants, hydraulic fluids, and other lubricating oil and grease compositions.

Compositions, when they contain these additives, are typically blended into a base oil in amounts such that the additives therein are effective to provide their normal attendant functions. Representative effective amounts of such additives are illustrated in TABLE 1. TABLE 1 Preferred More Preferred Additives Weight % Weight % V.I. Improver    1-12  1-4 Corrosion Inhibitor 0.01-3 0.01-1.5 Oxidation Inhibitor 0.01-5 0.01-1.5 Dispersant  0.1-10 0.1-5  Lube Oil Flow Improver 0.01-2 0.01-1.5 Detergent/Rust Inhibitor 0.01-6 0.01-3   Pour Point Depressant   0.01-1.5 0.01-0.5 Anti-foaming Agents  0.001-0.1 0.001-0.01 Anti-wear Agents 0.001-5  0.001-1.5  Seal Swell Agents  0.1-8 0.1-4  Friction Modifiers 0.01-3 0.01-1.5 Lubricating Base Oil Balance Balance

When other additives are employed, it may be desirable, although not necessary, to prepare additive concentrates comprising concentrated solutions or dispersions of the subject additives of the present invention (in concentrate amounts hereinabove described), together with one or more of said other additives (said concentrate when constituting an additive mixture being referred to herein as an additive-package) whereby several additives can be added simultaneously to the base oil to form the lubricating oil composition. Dissolution of the additive concentrate into the lubricating oil can be facilitated by solvents and by mixing accompanied by mild heating, but this is not essential. The concentrate or additive-package will typically be formulated to contain the additives in proper amounts to provide the desired concentration in the final formulation when the additive-package is combined with a predetermined amount of base lubricant. Thus, the subject additives of the present invention can be added to small amounts of base oil or other compatible solvents along with other desirable additives to form additive-packages containing active ingredients in collective amounts of, typically, from about 2.5 to about 90 percent, preferably from about 15 to about 75 percent, and more preferably from about 25 percent to about 60 percent by weight additives in the appropriate proportions with the remainder being base oil. The final formulations can typically employ about 1 to 20 weight percent of the additive-package with the remainder being base oil.

All of the weight percentages expressed herein (unless otherwise indicated) are based on the active ingredient (AI) content of the additive, and/or upon the total weight of any additive-package, or formulation, which will be the sum of the AI weight of each additive plus the weight of total oil or diluent.

The epoxidized ester is present in the compositions of the present invention in a concentration in the range of from about 0.01 to about 10 weight percent. In general, the lubricant compositions of the invention contain the additives in a concentration ranging from about 0.05 to about 30 weight percent. A concentration range for the additives ranging from about 0.1 to about 10 weight percent based on the total weight of the oil composition is preferred. A more preferred concentration range is from about 0.2 to about 5 weight percent. Oil concentrates of the additives can contain from about 1 to about 75 weight percent of the additive reaction product in a carrier or diluent oil of lubricating oil viscosity.

In general, the additives of the present invention are useful in a variety of lubricating oil base stocks. The lubricating oil base stock is any natural or synthetic lubricating oil base stock fraction having a kinematic viscosity at 100° C. of about 2 to about 200 cSt, more preferably about 3 to about 150 cSt, and most preferably about 3 to about 100 cSt. The lubricating oil base stock can be derived from natural lubricating oils, synthetic lubricating oils, or mixtures thereof. Suitable lubricating oil base stocks include base stocks obtained by isomerization of synthetic wax and wax, as well as hydrocracked base stocks produced by hydrocracking (rather than solvent extracting) the aromatic and polar components of the crude. Natural lubricating oils include animal oils, such as lard oil, vegetable oils (e.g., canola oils, castor oils, sunflower oils), petroleum oils, mineral oils, and oils derived from coal or shale.

Synthetic oils include hydrocarbon oils and halo-substituted hydrocarbon oils, such as polymerized and interpolymerized olefins, gas-to-liquids prepared by Fischer-Tropsch technology, alkylbenzenes, polyphenyls, alkylated diphenyl ethers, alkylated diphenyl sulfides, as well as their derivatives, analogs, homologs, and the like. Synthetic lubricating oils also include alkylene oxide polymers, interpolymers, copolymers, and derivatives thereof, wherein the terminal hydroxyl groups have been modified by esterification, etherification, and the like.

Another suitable class of synthetic lubricating oils comprises the esters of dicarboxylic acids with a variety of alcohols. Esters useful as synthetic oils also include those made from C₅ to C₁₂ monocarboxylic acids and polyols and polyol ethers. Other esters useful as synthetic oils include those made from copolymers of α-olefins and dicarboxylic acids which are esterified with short or medium chain length alcohols. The following are exemplary of such additives and are commercially available from Akzo Nobel Chemicals SpA: Ketjenlubes 115, 135, 165, 1300, 2300, 2700, 305, 445, 502, 522, and 6300, among others.

Silicon-based oils, such as the polyalkyl-, polyaryl-, polyalkoxy-, or polyaryloxy-siloxane oils and silicate oils, comprise another useful class of synthetic lubricating oils. Other synthetic lubricating oils include liquid esters of phosphorus-containing acids, polymeric tetrahydrofurans, poly α-olefins, and the like.

The lubricating oil may be derived from unrefined, refined, re-refined oils, or mixtures thereof. Unrefined oils are obtained directly from a natural source or synthetic source (e.g., coal, shale, or tar and bitumen) without further purification or treatment. Examples of unrefined oils include a shale oil obtained directly from a retorting operation, a petroleum oil obtained directly from distillation, or an ester oil obtained directly from an esterification process, each of which is then used without further treatment. Refined oils are similar to unrefined oils, except that refined oils have been treated in one or more purification steps to improve one or more properties. Suitable purification techniques include distillation, hydrotreating, dewaxing, solvent extraction, acid or base extraction, filtration, percolation, and the like, all of which are well-known to those skilled in the art. Re-refined oils are obtained by treating refined oils in processes similar to those used to obtain the refined oils. These re-refined oils are also known as reclaimed or reprocessed oils and often are additionally processed by techniques for removal of spent additives and oil breakdown products.

Lubricating oil base stocks derived from the hydroisomerization of wax may also be used, either alone or in combination with the aforesaid natural and/or synthetic base stocks. Such wax isomerate oil is produced by the hydroisomerization of natural or synthetic waxes or mixtures thereof over a hydroisomerization catalyst. Natural waxes are typically the slack waxes recovered by the solvent dewaxing of mineral oils; synthetic waxes are typically the wax produced by the Fischer-Tropsch process. The resulting isomerate product is typically subjected to solvent dewaxing and fractionation to recover various fractions having a specific viscosity range. Wax isomerate is also characterized by possessing very high viscosity indices, generally having a VI of at least 130, preferably at least 135 or higher and, following dewaxing, a pour point of about −20° C. or lower.

The additives of the present invention are especially useful as components in many different lubricating oil compositions. The additives can be included in a variety of oils with lubricating viscosity, including natural and synthetic lubricating oils and mixtures thereof. The additives can be included in crankcase lubricating oils for spark-ignited and compression-ignited internal combustion engines. The compositions can also be used in gas engine lubricants, turbine lubricants, automatic transmission fluids, gear lubricants, compressor lubricants, metal-working lubricants, hydraulic fluids, and other lubricating oil and grease compositions. The additives can also be used in motor fuel compositions.

The advantages and the important features of the present invention will be more apparent from the following examples.

EXAMPLES

Pb & Cu Corrosion Testing

The results of a Cummins bench test for measuring the degree of Cu and Pb corrosion of an oil formulation using an American Petroleum Institute (API) Group II base stock are shown in Table 1. The Cummins bench test is part of the API CH-4 category for diesel engine oils. Four metal coupons (25.4 mm squares) of pure lead, copper, tin, and phosphor-bronze are immersed in 100 mL of oil at 121° C. with air bubbling through (5 L/hr) for 168 hours. The used oil is analyzed for metals and the copper sample is examined for discoloration. The limits for API CH-4 are 20 ppm Cu, 120 ppm Pb, 50 ppm Sn in used oil and 3 max for the ASTM D 130 rating of the copper square. Additives were blended into a fully formulated SAE 15W-40 oil with API CI-4 and CH-4 credentials.

In the first row of Table 1 are data generated on the SAE 15W-40 oil without any top treat of other additives. In the next row is seen the increase in lead corrosion that results from adding 1 wt % of glycerol monooleate friction modifier. The data in the third row illustrate the reduction in lead corrosion that is achieved with the addition of the epoxidized 2-ethyl hexyl tallate anti-corrosion additive of the present invention. TABLE 1 ASTM D 5968 Corrosion Bench Test of Engine Oil at 121° C Additive Wt % (in Rotella T SAE 15W-40) Additive Cu ppm Pb ppm ASTM D130 Reference 0.0 7 11.9 1b Glycerol monooleate 1.0 10 81.4 1b Glycerol monooleate 1.0 7.5 4.0 1b Drapex 4.4 1.0

In view of the many changes and modifications that can be made without departing from principles underlying the invention, reference should be made to the appended claims for an understanding of the scope of the protection to be afforded the invention. 

1. A composition comprising: (A) a lubricant or a hydrocarbon fuel, and (B) at least one epoxidized ester of the formula:

wherein: m is 1 to 36; R₁ and R₂ are independently selected hydrocarbyl groups, optionally substituted with alkyl, cycloalkyl, alkenyl, aryl or alkoxy groups, and optionally containing OH, ether, or epoxide functionalities, or R₁ is a polyol residue selected from the group consisting of

wherein: n is O to about 12; R₄, R₅, and R₉ are independently selected from the group consisting of hydrogen and hydrocarbyl; R₆ is selected from the group consisting of linear alkylene, branched alkylene, linear alkenyl, and branched alkenyl; and R₃, R₇, and R₈ are independently selected from the group consisting of hydrogen and an acyl group of the form:

wherein R₁₀ is hydrocarbyl, which may be further substituted.
 2. The composition of claim 1 further comprising an additive that is corrosive to lead and/or copper.
 3. The composition of claim 2 wherein the corrosive additive is selected from the group consisting of glycerol monooleate, partially hydrolyzed vegetable oils, full and partial esterification products of diols and polyols with and C₆-C₃₆ carboxylic acids, C₆-C₅₀ carboxylic acids, amides derived from C₆-C₅₀ carboxylic acids, esters of hydroxypolycarboxylic acids, tetraalkyl thiuram disulfides, thionamides, thioureas, dithiocarbamates, hydrazides, succinylhydrazides, 4-imidazolidine thiones, 1,3,4-oxadiazole-2(3H)-thiones, 1,3,4-thiadiazolane-2-thiones, 2,3-dihydro-1,3,4-oxadiazoles, and mixed thio acid amide molybdenum complexes.
 4. The composition of claim 1 wherein the epoxidized ester is an ester of a C₆-C₂₂ unsaturated or polyunsaturated carboxylic acid or mixtures thereof.
 5. The composition of claim 1 wherein the epoxidized ester is an ester of epoxidized oleic or linoleic acid, or a mixture thereof.
 6. The composition of claim 1 wherein the epoxidized ester is an epoxidized C₄-C₁₂ ester of oleic or linoleic acid, or mixture thereof.
 7. The composition of claim 1 wherein the epoxidized ester is epoxidized 2-ethylhexyl tallate
 8. The composition of claim 1 wherein the epoxidized ester is an epoxidized vegetable oil.
 9. The composition of claim 1 wherein the epoxidized ester is selected from the group consisting of epoxidized soybean oil, epoxidized canola oil, and mixtures thereof.
 10. The composition of claim 2 wherein the corrosive additive is glycerol monooleate.
 11. The composition of claim 2 wherein the corrosive additive is selected from the group consisting of dithiocarbamates and thiuram disulfides.
 12. The composition of claim 2 wherein the corrosive additive is a 4-imidazolidine thione.
 13. The composition of claim 2 wherein the corrosive additive is selected from the group consisting of hydrazides, succinylhydrazides, 1,3,4-oxadiazole-2(3H)-thione, 1,3,4-thiadiazolane-2-thione, 2,3-dihydro-1,3,4-oxadiazole, and amides derived from C₆-C₅₀ carboxylic acids.
 14. The composition of claim 2 wherein the corrosive additive is selected from the group consisting of partially hydrolyzed vegetable oils, full and partial esterification products of diols and polyols with and C₆-C₃₆ carboxylic acids and mixtures thereof, and esters of hydroxypolycarboxylic acids.
 15. The composition of claim 2 wherein the corrosive additive is a triester of citric acid.
 16. The composition of claim 2 wherein the corrosive additive is glycerol monooleate and the epoxidized ester is epoxidized 2-ethylhexyl oleate.
 17. A method for improving the anti-corrosive, anti-fatigue, and anti-wear properties of lubricants and hydrocarbon fuels comprising adding to said lubricants and hydrocarbon fuels a functional property-improving amount of at least one at least one epoxidized ester of the formula:

wherein: m is 1 to 36; R₁ and R₂ are independently selected hydrocarbyl groups, optionally substituted with alkyl, cycloalkyl, alkenyl, aryl or alkoxy groups, and optionally containing OH, ether, or epoxide functionalities, or R₁ is a polyol residue selected from the group consisting of

wherein: n is 0 to about 12; R₄, R₅, and R₉ are independently selected from the group consisting of hydrogen and hydrocarbyl; R₆ is selected from the group consisting of linear alkylene, branched alkylene, linear alkenyl, and branched alkenyl; and R₃, R₇, and R₈ are independently selected from the group consisting of hydrogen and an acyl group of the formula:

wherein R₁₀ is hydrocarbyl, which may be further substituted.
 18. The method of claim 17 wherein the epoxidized ester is an epoxidized ester of a C₆-C₂₂ unsaturated or polyunsaturated carboxylic acid or mixtures thereof.
 19. The method of claim 17 wherein the epoxidized ester is an epoxidized ester of oleic or linoleic acid, or a mixture thereof.
 20. The method of claim 17 wherein the epoxidized ester is epoxidized 2-ethylhexyl tallate 